<html><body><form action="b.php" method="POST">输入相应ID值:<input type="text" name="a" value="115921"><input type="submit"></form></body></html>
<html><body><?php $t=$_POST["a"]; echo "$t"; ?><a href=c.php>c</a></body></html>
<?php
$t=$_POST['a'];
echo $t;
echo '<a href=c.php?b='.$t.'>c</a>
c.php
<?php
$c=$_REQUESP['b'];//你也可以用$_POST
echo $c;